[BUG] cannot create/send multipart POST REST request (from file)

[ghost]

What is the bug? A clear and concise description of the bug.

How can one reproduce the bug? Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Enter following curl command '...'
4. See error

What is the expected behavior? A clear and concise description of what you expected to happen.

What is your host/environment?

• OS: [e.g. ubuntu]
• Version [e.g. 20.10]
• Plugin version [e.g. 1.1.0]
• OpenSearch version[e.g. 1.0.0]

Do you have any screenshots? If applicable, add screenshots to help explain your problem.

Do you have any additional context? Add any other context about the problem.

[dblock]

Catch All Triage - 1 2 3 4 5

[dblock]

Closing, not enough detail of what's happening here.